2 days ago i upgraded (reinstalled) Win7-64 and then Photoshop cs4-64 could not be started anymore.
i reinstalled Ps. with the same result again.

Yesterday, i reinstalled Win7 again and then Ps. again.
same result.

every time i try to start Ps. a notice says: Photoshop was unable to start correctly (0xc000007b).

i looked that kind of error on the Internet and there are many answers, both complicated and simple ones.
One of them said that most probably the reason was in - Component services/services (local) - there was a badly configured service.
I reviewed all the services and think they're ok, but i can't be sure about that.
then i uninstalled Ps. and cleaned up everything in the registry that pertained to Ps, as also on C drive.

then i reinstalled Ps, but i still can't use it, the same error showed up.

the only thing left for me to do is to wipe C drive and reinstall W7 and all my programs; something i don't like to do;

with the help from friends, i've found and looked at some says to correct this problem - complicated solutions - , but with my limited understanding of computer programs,
i will think a bit about those different solutions and i most probably will reinstall everything from a blank slate, beginning with W7 and right after that with Ps.

after that, i will check if Ps can be opened after finishing installation of any other program, which should point out which one, including W7 updates, causes the problem.